The present invention relates to a table comprising a trestle, a table top supported movably by the trestle, and a device for adjusting the height of the table top, at least at one edge thereof, relative to the trestle.
Tables with table tops that can be adjusted as regards their height and/or their inclination have been previously known in various forms. Such a table with a table top that can be adjusted in height, provides the possibility of adapting the height of the table top to particular requirements of a person using the table, while a table equipped with a table top whose inclination can be adjusted provides the possibility of bringing a normally horizontal table top into a more convenient inclined position for writing or drawing purposes. Except for tables equipped with relatively expensive mechanical drive mechanisms for table-top adjustments, these tables are normally equipped with snap-in locking devices which are troublesome to operate, and this often prevents users from making practical use of such adjusting facilities.
Now, it is an object of the present invention to provide a table of the type described above in which adjustment of a table top is not connected with troublesome maneuvers, while on the other hand a device for adjusting the height or the inclination of the table top does not require great input, and/or particularly complex drive mechanisms. At the same time, the invention is directed to ensuring a secure fixing of the table top in a desired position.
This object is achieved according to the invention by the fact that at least one abutment is fixed to the trestle beneath the table top which coacts with a wedge-shaped intermediate piece which is arranged for being displaced in an opening direction of its angle, substantially parallel to the table top, and which can be introduced in this way a lesser or greater distance into a space between the abutment and the table top so that the distance between the table top and the abutment and, thus, the position of the table top relative to the trestle, are determined by the position of the intermediate piece.
The table top of the table according to the invention, therefore, is fixed in the selected position by the wedge-shaped intermediate piece which retains it, as a function of its selected position, at a defined distance from an abutment fastened to the trestle. The intermediate piece may also assume a position in which the table top rests directly on the abutment, in which case the distance between the table top and the abutment defined by the intermediate piece is equal to zero so that the lowest position of the table top is defined by the abutment.
Arranging a wedge-shaped intermediate piece does not present any difficulties. Simple guide devices will suffice for holding the intermediate piece, because such guide devices need not absorb any notable forces, the pressure being transmitted simply for the table top via the intermediate piece to the abutment fixed to the trestle. Although the table top rests on the intermediate piece, and the latter rests on the abutment substantially loosely, the table top is still retained safely in the selected position, being always loaded from above so that it will be sufficient to support it solidly from below. These requirements are absolutely fulfilled by the use of an abutment which supports the table top directly, or indirectly via the intermediate piece. When the table top is in an unloaded condition, the intermediate piece may be introduced, as desired, a lesser or greater distance, or degree, between the table top and the abutment. This makes handling of the table extremely simple. The intermediate piece may be mounted selectively either on the table top or on the trestle, and there are many different possibilities of supporting such an intermediate piece in movable relationship so that it can be introduced into, or withdrawn from the space between the table top and the abutment as desired. In the simplest of all cases the wedge-shaped intermediate piece may be mounted at the end of a pusher rod which provides a user with simple means for moving the intermediate piece by means of the pusher rod. Such a pusher rod would also make it possible to interconnect several such wedge-type intermediate pieces, for common operation. Such an arrangement would be particularly desirable in cases where parallel raising or lowering of the table top is desired, by means of several abutments and intermediate pieces arranged on an edge of the table top.
In the simplest of all cases, a table designed according to the invention may comprise a table top arranged for assuming, selectively, one of two defined positions, i.e. a lower position in which the table top rests directly on the abutment, or an upper position in which the wedge-shaped intermediate piece has been fully inserted into the space between the abutment and the table top. On the other hand, a particular advantage of the wedge shape is that it enables the position of the table top to be varied in small steps, or even infinitely, by varying the position of the wedge relative to the abutment.
In order to ensure efficient power transmission between the wedge-shaped intermediate piece and the adjoining components, the contact surface should be as large as possible. According to one preferred embodiment of the invention, therefore, the wedge-shaped intermediate piece comprises a first wedge surface extending in parallel to the direction of displacement and a second wedge surface extending at an angle relative to the first wedge surface, the second wedge surface being in contact with an oblique surface extending in parallel thereto, in at least one defined position of the table top. In the case of this embodiment of the invention, the first wedge surface forms a plane contact surface for a counterface extending in parallel to the direction of displacement, while the second wedge surface also comes into full surface contact with an oblique surface extending in parallel to the second wedge surface and provided specifically for this purpose. It is not necessary in this case that the second wedge surface and the mating oblique surface be absolutely planes. Rather, they may advantageously be designed as cylindrical surfaces whose generating lines extend in parallel to the legs of the wedge angle so that one obtains a formlocking engagement, in transverse direction to the direction of displacement of the intermediate piece, which does away with a need to secure the table top on the trestle against displacement in a direction perpendicular to the direction of movement of the intermediate piece. The wedge surface and the mating oblique surface may, preferably, be designed as circular cylindrical surfaces of substantially equal radii.
As has been mentioned above, the invention can be applied with advantage to tables whose table tops can be adjusted in inclination. The table top of such a table is, preferably, hinged at its rear edge, and the inclination of the table top can be varied by vertical adjustment of the table top in the area of its forward edge. A table of this type known heretofore was connected with a disadvantage that its table top, which was hinged at its rear edge, was supported at its forward edge so that the trestle always had to be provided with supporting parts reaching right to the forward edge of the table top. However, modern tables of this type used, for example, as desks in offices, often comprise trestles consisting substantially of two side parts with feet and supporting members serving for interconnecting such side parts and being arranged in areas of rear edges of table tops.
The invention provides the particular advantage that it can be implemented also in connection with such trestles. According to a preferred embodiment of a table, whose table top is hinged in the area of its rear edge, the abutment is arranged near the rear edge of the table top. The abutment comprises an oblique surface on which the table top rests in its lowermost position. The table top can then be raised from this lowermost position up to a horizontal position, by inserting the wedge-shaped intermediate piece between the abutment and the table top.
Especially in this embodiment of the invention it may be convenient to arrange the wedge-shaped intermediate piece at an end of a pusher rod mounted on a lower face of the table top and extending to the latter's forward edge. It is then easily possible to lift the table top at its forward edge, for adjusting purposes, and to introduce or withdraw the intermediate piece as required, by actuating the pusher rod. This process may even be facilitated by a spring loaded pusher rod.
According to a preferred embodiment of the invention, the pusher rod is guided in a bearing block mounted on a lower face of the table top. Its end opposite the intermediate piece is provided with a handle, and the rod is surrounded by a spiral compression spring acting between the bearing block and the intermediate piece.
It is a general requirement, in particular with respect to office furniture, that their surface structure and color should be adaptable to existing furniture and equipment. Consequently, it has been general practice to design office tables in such a manner that a standard trestle can be provided with table tops of different kinds. This possibility is provided also for a table according to the invention when, according to a further improvement of the invention, a lower face of the table top is equipped with at least one hollow beam extending perpendicularly to the rear edge of the table top, the abutment projects into the rear end of the hollow beam, and the pusher rod with the intermediate piece are located inside the hollow beam, for movement in the latter's longitudinal direction. The abutment and the hollow beam may be arranged on a corresponding crossbar of the trestle so that different table tops, as desired by the customers, can be fastened to such a hollow beam. Advantageously, the hollow beam may be articulated on the abutment projecting into its rear end.
In the case of tables where the table top comprises a supporting beam extending in parallel to the at least one vertically adjustable edge of the table top, a particularly simple and, at the same time, sturdy design of the adjusting mechanism can be achieved if at least one wedge-shaped intermediate piece is arranged for displacement in the longitudinal direction of the supporting beam, and a wedge-shaped piece complementary to and coacting with the intermediate piece is arranged on the lower face of the table top and provided with a surface which is inclined relative to the table top and which forms a contact surface for a second wedge surface of the intermediate piece. The table top is then supported by a sturdy supporting beam, directly at its vertically adjustable edge, so that the table top is capable of carrying very high loads, without requiring any particular arrangements securing its stability, as required in cases where cantilever arms are used for supporting the table top.
Depending on the length of the table top, the arrangement of a single intermediate piece between the supporting beam and the table top may be sufficient, or several such intermediate pieces may be required. According to a particularly preferred embodiment of the invention, two intermediate pieces are provided in spaced arrangement in the area of the vertically adjustable edge of the table top, each of them coacting with a complementary wedge-shaped piece, and the two of them being interconnected by a pusher rod extending in parallel to the edge of the table top.
In order to securely prevent, even in cases of high loads, that the wedge-shaped intermediate piece may be pressed out from between the abutment and the table top, it may be convenient to provide several discrete locking positions for the wedge-shaped intermediate piece. Such locking positions may be implemented easily in the case of the last-mentioned preferred embodiment of the invention by an arrangement in which the pusher rod interconnecting the intermediate pieces is provided with a radially projecting handle and the supporting beam of the trestle, on which the intermediate pieces are arranged to slide, comprises a plurality of spaced openings into which the handle can be introduced and which define locking positions of the wedge-shaped intermediate pieces.